Send on delta

Send on delta is a mechanism for throttling output network variable updates based on value changes. It specifies the minimum change in value that must occur before the network variable is updated, within the constraint of minimum send time. If the difference between the current value and the last updated value, at the instant the minimum send time interval elapses, is less than the send on delta value, then the network variable is not updated.

There is an exception to this rule for network variable types SNVT_scene, SNVT_preset, SNVT_alarm, SNVT_alarm2 and all UNVTs. Network variables of these types are updated if they are written to by the device firmware whether or not the value changes, within the constraint of minimum send time.

SCPTsendDelta is the configuration property for send on delta. In version 1.72 and greater, the default value for send on delta is a non-zero value dependent on network variable type. For example, the send on delta value for SNVT_temp_p is 0.2 degrees F, for SNVT_lev_percent it is 1%. Setting this property to zero eliminates throttling based on send on delta.